<span>а) 1+sin a = 2cos²(45°- a/2)
1+sina=2*(1+cos(90-a))/2=1+sina</span>
<span>1+sina=</span><span><span>1+sina
</span>формула cos²a=(1-cos2a)/2
b) 2sin²(45°- a) + sin 2a = 1
2(1-cos(90-2a))/2+sin2a=1-sin2a+sin2a=1
1=1
c) 1 - sin a = 2 sin²(45°- a/2)
1-sina=2(1-cosa)/2=1-sina
1-sina=1-sina
</span>
<span>P-1/4=3/8+1/4</span>
<span>P-1/4=5/8</span>
P=1/4+5/8
<span>P=7/8</span>
А)= 4(а+2б)/ 4б = а+2б/б
б)= 5(х-2у)/3(х-2у)= 5/3
в)= 3х(2х-1)/4(1-2х)= 3х(2х-1)/ -4(2х-1)= - 3х/4
г) = b^2/b^2=b